A biologically friendly single step method for gold nanoparticle formation

There has been a keen interest for developing a biologically friendly approach for the preparation of gold nanoparticles for their application reasons. A biocompatible, quick and single step method is established for the preparation of gold nanoparticles in lecithin (Egg phosphatidylcholine)/water systems where lecithin itself acts as a reductant for hydrogen tetrachloro aurate (HAuCl4) to form the gold nanoparticles. Small gold nanoparticles (5–7 nm in diameter) were prepared in lamellar phases formed by lecithin within 6–7 h of HAuCl4 addition. Sonication of aqueous mixture of lecithin/HAuCl4 reduces the time of reduction process to seconds when a sonicator with probe (100 W) is used. Most of the particles are found attached to lecithin structures and are comparatively large in size. Some 10 nm particles are found attached to small lecithin vesicles (∼100 nm) formed during sonication. The nanoparticles formed were stabilized by an anionic surfactant sodium dodecylsulfate (SDS) which proved to be a good stabilizer, the nanoparticles being stable up to six months. To the best of our knowledge, this is the first report where a biological surfactant lecithin itself has acted as a reductant and no other chemical reductants were required for the gold nanoparticle formation. Particles were characterized by Uv–vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). Lamellar phases were characterized by a polarizing microscope.